SPATIALREG Procedure
SPATIALEFFECTS Statement
SPATIALEFFECTS <model-spatial-effect-regressors> </options>;
The SPATIALEFFECTS statement enables you to specify covariates (such as X) whose spatial lag, WX, is to be added to the MODEL statement.
PROC SPATIALREG adds the spatially weighted model-spatial-effect-regressors to regressors that are specified in the MODEL statement. For example, if you specify q variables 
in the SPATIALEFFECTS statement, then each of q spatially weighted variables, as represented by each column of 
, has a parameter to be included in the regression. Here, denotes the matrix product of 
and 
. In addition, is the design matrix formed by the q variables . The spatial weights matrix comes from the data set that is specified in the WMAT= option. The "Parameter Estimates" table in the displayed output shows the estimates for spatially weighted model-spatial-effect-regressors; they are labeled with the prefix "W_". For example, if you specify z (a variable in your primary data set) as a spatial effect explanatory variable, then the "Parameter Estimates" table labels the corresponding parameter estimate "W_z".